Pueraria mirifica, a leguminous plant found mainly in Thailand, was introduced to the West in the 1930s and has been used as a Thai folk medicine for invigorating sexual activities (Nature, Dec. 3, 1960, 774). Particularly, its tubers have long been used for invigorating post-menopausal females.
Butea superba is also a leguminous plant found mainly in Thailand. This plant provides red sap and its tubers have long been used as a raw material for invigorating males in Thailand.
Mucuna collettii is a tall leguminous plant found mainly in the subtropical zones. When being cut and exposed to the air, all parts of this plant turn black. Likewise, its roots have long been used as a folk medicine for invigorating males.
In those plants are found 25 or more compounds, including miroesterol, diadzin, diadzein, genistin, genistein, beta-sitosterol, stigrmsterol, mirificoumestan, kwarkhurin, mirificine, long chain alcohols, and 5-dioxyisoflavone. Particularly, those plants are found to contain phytoestrogen in far larger quantities than do other leguminous plants.
Isoflavones are distributed in a variety of plants and extensively found particularly in such leguminous plants as soybean, arrowroot and alfafa. Isoflavones are termed phytoesterogens on the grounds that not only do these compounds have structures similar to those of endogenous estrogens, but also their physiological actions bring about the same effects as those of estrogens. Phytoestrogens, however, show insignificant physiological activity compared with estrogens. Where phytoestrogens are ingested for a long period of time, it is reported that estrogen hormone-like functions are exerted in the body (Bingham S A, Atkinson C, J. Nutr 1988 79(5) 393–406). In terms of subgroups, phytoestrogens may be broken down into cou-mestrol, genistgein, formonetin, diadzein, biochanin A, most of which are based on isoflavone.
There was reported one interesting study concerning phytoestrogen, in which attention was paid to the fact that Japanese women suffer from less serious menopausal diseases than do Western women. This has been revealed to be attributed to the diet of the Japanese, who consume soybean related foods containing much of phytoestrogen. Now, the use of phytoestrogen in overcoming menopausal disease is now under extensive study. Genistein, a phytoestrogenic material which can be extracted from leguminous plants, for example, is prescribed to overcome a menopausal disease. This compound is also used to prevent breast cancer or cardiovascular diseases. Additionally, diosgenin, a precursor to progesterone which is responsible for the menstrual cycle, is now commercially available as a cream formulation while being extracted from Mexican wild yams. There have successively been reported noteworthy research results on the effects of phytoestrogen on the reduction of breast cancer attack rate. In the case of Asian women, they are attacked by breast cancer, ovarian cancer, and uterine cancer less than women of the other regions since they have long consumed foods prepared from leguminous plants, which contain much phytoestrogen (Adlercreutz H, Honjo H., Am. J. Clin. Nutri. 1991, 54(6), 1093–1100).
Furthermore, phytoestrogen is known to be of anti-oxidative activity as well as being active in preventing or improving osteoporosis (Tsutsmi N, Biol. Pharm. bull 1995, 18(7) 1012–1015). In vivo, phytoestrogen binds to an estrogen receptor, showing an estrogen agonist or antagonist activity. The level at which estrogen is produced in vivo can be elucidated with the affinity for the binder. At the time of menopause, because estrogen is produced in a very small quantity, phytoestrogen's action may be relatively increased. Generally, phytoestrogen has a hormonal activity which is nothing but 1/400 to 1/1000 that of estrodiol's. However, this low activity has the advantage of showing no side effects that estrogen has. Hence, when having long been ingested, phytoestrogen is recognized as preventing the side effects estrogen can bring about, as demonstrated in various research results. Despite many research results, the accurate therapeutic mechanism and effects associated with phytoestrogen have not yet been discovered.
One of the findings disclosed as to phytoestrogen, thus far, is the physiological activity upon application to the skin. While estrogen was applied to the skin of menopausal females, who are generally in rapid progression of dermal aging, it was observed that their skin was inhibited from progressing into senility. In detail, after 6 months of the application of estrogen, the skin noticeably became resilient with a 60% improvement in the depth of wrinkles. This effect was reported to be attributed to an increase in the number of dermal collagen fibers (Schmidt J B, Binder M., Int. J. Dermatol., 1996, 35(9), 669–674).
Composing the hypoderm, elastin tissues form a network, along with collagen tissues, in the skin. Elastase, a protease which hydrolyses elastin, is known to play an important role in the anti-inflammatory mechanism. This enzyme attacks all proteins which act to maintain the backbone and shape of the connective tissues, such as elastin, collagen, proteoglycan and keratin, nonselectively as well as indiscriminately. Collagenase is known to exert its catalytic action on a limited number of substrates (Wiedow, O., Schroder, J. M., E. J. Biol. Chem. 265(25), 14791 (1990)). Exposure to UV-A makes the skin suffer repeatedly from mild inflammation in response of the catalytic action of elastase on reticular tissues and brings about damage in elastin and collagen fibers, finally making the skin sag (Motoyoshi, K., Tacenouch, M., Proceedings of the 19th IFSCC Congress Sydney 22–25, Oct. 1996). Beginning in their forties, people generally have their skin rapidly decrease in resilience. From a biochemical point of view, as people grow older, elastase is increasingly active in the body, which results in destroying or aggregating a part of the elastin fibers and losing of collagen fibers (Bissett, D. L., Photochem. Photobiol., 1987, 46, 367–378). Recently, extensive research has been directed to the finding of inhibitory materials against elastase activity. For instance, cosmetics for topical application are commercially available, which contain elastase inhibitory materials in order to prevent the skin from being xeric owing to UV irritation or to inhibit the skin from progressing into senility. Particularly, plant extracts with anti-oxidation activity are under the intensive study on the retardation of dermal aging or wrinkling because they have been discovered to inhibit activity of elastase (Bizot-Foulon V., Godeat G., W. Int. J. Cos. Sci. 17, 225–264 (1995)).